1. Field of the Invention
The present invention relates generally to a magnetic disk drive, and more particularly to a cover structure of the magnetic disk drive.
2. Description of the Related Art
In a magnetic disk drive for a computer, a contact start and stop (CSS) system is generally adopted as the relation between a magnetic head and a magnetic disk. This system is such that while the disk is rotating, the head is kept flying above the disk at a microscopic height owing to the balance between a flying force applied to the head by an air flow generated by high-speed rotation of the disk and an elastic force of a suspension pressing the head on the disk. When the disk rotation is stopped, the head is moved to a contact zone formed on the disk and comes into contact with the disk at the contact zone. While the disk is at rest, the head and the disk are kept in contact with each other.
As mentioned above, the head is kept flying above the disk at a microscopic height during rotation of the disk. Accordingly, there is a possibility of a head crash or the like due to of dust or the like. To cope with this problem, the magnetic disk and the magnetic head for reading/writing data on the disk are enclosed in a sealed housing (disk enclosure). The housing is composed of a base and a cover fixed through a packing to the base by a plurality of screws. The cover of a conventional magnetic disk drive is a cast cover manufactured primarily by aluminum die casting. A metal sheet is mounted on the cover to reduce noise.
However, it is difficult to accurately manufacture an aluminum cast cover having a complicated shape. It has accordingly been considered using resin for the cover material because of its good moldability, thereby realizing a complicated shape. However, such a resin-only cover is inferior in its electromagnetic shielding effect to a metal cover, causing the possibility of a malfunction or the like of the disk drive due to external electromagnetic waves. Further, the resin-only cover is lighter in weight than the metal cover, causing an increase in noise from the disk drive. Thus, the resin-only cover is not satisfactory in noise reduction. Further, the resin-only cover is prone to charge static electricity, so that there is a high possibility of an IC crash, a head crash, etc. due to the static electricity. It is therefore necessary to provide protection against static electricity.
In the conventional magnetic disk drive, a printed wiring board on which a control circuit or the like for the disk drive is exposed to the outside of the housing. Accordingly, there is a possibility that electromagnetic waves generated from the printed wiring board could have adverse effects on the surroundings, e.g., an adverse effect on a pacemaker or an adverse effect on an unborn child in a pregnant woman.
It is therefore an object of the present invention to provide a disk drive having a resin cover which can provide electromagnetic protection and reduce noise from the disk drive.
In accordance with an aspect of the present invention, there is provided a disk drive comprising a housing having a base and a cover fixed to the base; a disk rotatably mounted in the housing and having a plurality of tracks; a head for reading/writing data on the disk; and an actuator for moving the head across the tracks of the disk; wherein the cover is composed of a molded resin and a metal sheet integrally embedded in the molded resin.
The cover is secured to the base by a plurality of screws. Preferably, the metal sheet of the cover is exposed at a portion where the screws are located. The metal sheet is a copper sheet or a steel sheet. The metal sheet may be formed as a meshed sheet. In this case, bonding strength between the metal sheet and the molded resin can be improved. Preferably, a noise absorbing member such as a polyurethane sheet is attached to the cover.
In accordance with another aspect of the present invention, there is provided a disk drive comprising a housing having a base and a first cover fixed to base; a disk rotatably mounted in said housing and having a plurality of tracks; a head for reading/writing data on the disk; an actuator for moving the head across the tracks of the disk; and a printed wiring board mounted below the base, on which a drive circuit is mounted; and a second cover fixed to the base so as to cover the printed wiring board; each of the first and second covers being composed of a molded resin and a metal sheet integrally embedded in the molded resin.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.